Properly conducted site characterizations are crucial to correctly determining the extent of contamination and for selecting the appropriate remediation strategy. They are conducted to understand what has previously occurred at the site, the extent of any contamination, and potential threats that still exist.


Old Union 76 LUST Site

On the Flathead Indian Reservation, Avanti conducted a site assessment to evaluate the extent of petroleum hydrocarbon contamination in the surficial, subsurface soils and groundwater onsite and surrounding the site. Avanti used data from the site investigation performed by a contractor in 2009 to refine the scope of our site assessment and advanced six soil borings, all of which were completed as monitoring wells. Based on the results of the assessment, petroleum hydrocarbons present in the soil were limited to the vicinity of the former pump islands. Avanti recommended that EPA: 1) continue to monitor the groundwater, and 2) implement and develop a pilot study program utilizing chemical oxidation as a remedial technology. EPA accepted these recommendations and the pilot ISCO event was initiated in July 2011.


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Custer’s Last Camp LUST Site

Avanti performed a site assessment on the Northern Cheyenne Indian Reservation in 2008. Three additional monitoring wells were installed, developed and sampled. Results from the site assessment indicated that petroleum hydrocarbons present in the soil were limited to the vicinity of the former pump islands. Avanti designed and performed an AS/SVE pilot study based on experience from similar sites. This resulted in the expeditious design and implementation of a full-scale AS/SVE system.